300M
is a low alloy, vacuum melted, steel of very high strength. Essentially it is a modified AISI 4340 steel with silicon, vanadium and slightly greater carbon and molybdenum content than 4340. 300M has a very good combination of strength (1900-2100 MPA after final heat treatment), toughness, fatigue strength and good ductility. 300M is a through hardening alloy.

Specific
Gravity

7.83
g/cm3

Typical
Applications

Related
Specifications

Aircraft
Landing Gear

Driveshafts

High
Strength bolts

Gears

AMS
6257

AMS
6417

AMS
6419

BS
S155

BMS
7-26

MTL
1201

MIL
S 8844

Chemical
Composition (Wt %)

C

Si

Mn

P

S

S+P

Cr

Mo

Ni

V

Min

0.39

1.5

0.6

-

-

-

0.7

0.3

1.65

0.05

Max

0.44

1.8

0.9

0.015

0.015

0.025

0.95

0.45

2

0.10

Typical Mechanical
Properties after heat treatment

0.2%
proof Stress

Tensile
Strength

Elongation

Reduction
of area

MPA

MPA

%

%

Min

Min

Max

Min

Min

Longitudinal

1550

1900

2100

8

30

Transverse

1550

1900

2100

5

20

Hardness
after heat treatment

534
- 601 HB

52
- 55 HRC

*
Every effort has been made to ensure
that our technical specifications are
accurate. However, technical specifications
included within Dynamic Metals Ltd should
be used as a guideline only and are
subject to change without notice.